/*
Author: CNH_Tourist
Status: Not submitted
*/
#include <bits/stdc++.h>
#pragma GCC optimization ("O3, unroll-loops")
using namespace std;
#define filename "test"
#define endl '\n'
#define X first
#define Y second
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define pii pair<int,int>
#define pll pair<ll,ll>
#define ll long long
#define ull unsigned long long
#define all(x) (x).begin(),(x).end()
#define BIT(x, i) (((x) >> (i)) & 1)
#define CBIT __builtin_popcount
#define gcd __gcd
void FileInOut()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
ifstream *fi = new ifstream (filename".inp");
ofstream *fo = new ofstream (filename".out");
if(*fi)
{
cin.rdbuf( fi->rdbuf() );
cout.rdbuf( fo->rdbuf() );
}
}
// unusual mod : 1000003999
// atan2(y, x): tinh goc tao boi oX va diem co toa do (x, y)
const int N = 100005;
int n, k;
int a[N];
vector<pii> v;
void Solve()
{
cin >> n >> k;
for(int i = 1; i <= n; i ++)
cin >> a[i];
for(int i = 1; i <= n; i ++) {
int fi = a[i];
int se = a[i] + 1;
if (i > 1 && a[i - 1] + 1 == a[i]) {
fi = v[v.size() - 1].X;
v.pop_back();
}
v.pb({fi, se});
}
// for(pii x : v) {
// cout << x.X << " " << x.Y << endl;
// }
for(int i = 0; i < v.size() - 1; i ++)
a[i] = v[i + 1].X - v[i].Y;
sort(a, a + v.size() - 1);
long long ans = n;
for(int i = 0; i < min((int)v.size() - k, (int)v.size() - 1); i ++) {
ans += a[i];
}
cout << ans;
}
int32_t main()
{
using namespace std::chrono;
auto start = high_resolution_clock::now();
FileInOut();
int test = 1;
// cin >> test;
while(test--)
Solve();
auto stop = high_resolution_clock::now();
auto duration = duration_cast<microseconds>(stop - start);
double t = duration.count() * 1.0 / 1000000;
// cout << endl << "Runtime: " << t << endl;
}
